Electric lamp envelope with pinch-sealed portion

ABSTRACT

A lamp envelope is formed with either one or more protrusions or one or more recesses or a combination of one or more protrusions with one or more recesses integral with the pinch-sealed portion or portions thereof in order to compensate for either an excess or deficiency in volume of glass. Uniform envelope length is thus achieved, thereby ensuring that the contact wires extending from the pinch-sealed ends of the glass envelope have the proper clearance from the envelope. In addition, internal stresses within the envelope are reduced.

United States Patent Inventor Leslie Wittek Belleville, NJ.

Appl. N 0. 756,730

Filed Aug. 20, 1968 Patented Jan. 26, 1971 Assignee Wagner Electric Corporation a corporation of Delaware Continuation-impart of application Ser. No. 662,026, Aug. 21, 1967, now abandoned.

ELECTRIC LAMP ENVELOPE WITH PINCH- SEALED PORTION 10 Claims, 9 Drawing Figs.

US. Cl..... 220/2.l

Int. Cl H0lk 61/30 l-lOlk 1/28 Field ofSearch 65/155,59,

[56] References Cited UNITED STATES PATENTS 2,816,398 12/1957 Pearson 65/138 2,965,698 12/1960 Gottschalk 65/59X 3,290,134 12/1966 Camarata 65/59X Primary Examiner-Raphael H. Schwartz Attorney-Eyre, Mann & Lucas SHEET 1 [1F 2 PATENTED JAN'26 1911 INVENT R [ESL/E hzrnsk ELECTRIC LAMP ENVELOPE WITH PINCII-SEALED PORTION The present application is filed on Aug. continuation-inpart of copending application Ser. No. 662,026 filed on Aug. 2 l 1967 and now abandoned by Leslie Witteh.

In the various processes for manufacturing lamps, particularly cartridge-type incandescent lamps, considerable difiiculty has been experienced in providing a uniform volume of glass at the ends of the lamps which are to be pinch sealed. Either as excess or a deficiency may and frequently doesoccur. When there is an excess, the heated glass is forced to flow toward the contact wires or toward the unheated rigid portion of the glass envelope under the prior art processes. This resulted in nonuniform length of the glass envelopes (too long), insufficient exposure of the contact wires, and the creation of high internal stresses within the glass envelope, which frequently resulted in breakage. When there is a deficiency, the contact wires are excessively exposed, making them more vulnerable to bending forces, and the glass envelopes are of nonuniform length (too short). Nonuniformity of envelope length can result in mounting difficulties, or even make mounting impossible in some cases. The present invention eliminates the aforementioned drawbacks and hazards resulting from either an excess of a deficiency in glass volume at the pinch-sealed portions of the glass envelope. A better understanding of the invention may be gained by referring to the figures described below.

FIG. 1 is a side view of a finished cartridge-type lamp and its relationship to the operative parts of a machine which carries out the manufacturing process. The rigid mounts 2 and 2' interlock with the contact wires d and 6 to maintain a proper spatial relationship between the contact wires within the envelope 8, and to support the filament 10. The upper and lower pairs of press jaws, 12 and 12' and M and 14' respectively, are provided with, for example, quarter hemisphere-shaped cutouts at the centers of the upper corners and 20' of pressjaws l2 and 12' and from the centers of the lower comers 22 and 22' of pressjaws l4 and 14. These cutouts provide lateral flow paths or channels for the soft, heated glass when the pressjaws l2, 12, I4 and I4 are pressed upon the upper and lower ends of the envelope to form a hermetic seal with lead wires 16 and 18.

This lateral flow diverts surplus glass into the cutouts and prevents glass from flowing against the mounts 2 and 2'. As a result, the contact wires 4 and 6 remain sufi'iciently exposed at the lamp ends and excessive internal stresses are avoided in the lamp, especially at the pressed ends. The glass which flows into the cutouts, which may vary in shape, forms protrusions 24 and 24' and 26 and 26' at each end of the envelope, these protrusions being symmetrical about the longitudinal axis of the lamp envelope.

FIG. 2 shows the finished cartridge lamp removed from the machine and rotated about its longitudinal axis 90 from the position shown in FIG. 1. Although the contact wires 4 and 6 are shown as being approximately triangular in shape, it will be readily understood by anyone skilled in the art that numerous other configurations mightbe effectively employed. The pinch-sealed ends 28 and 30 of the envelope 8 have a width approximately the same as the diameter of the tubular portion 32 of the envelope 8.

The FIGS. described below illustrate alternative forms and locations of protrusions or recesses in the pinch-sealed portion of the lamp.

FIG. 3 is a side view and a front view of a finished cartridgetype lamp having point protrusions extending from the pinchsealed portions, the protrusions being located at an intermediate position between the inner and outer sealed edges of the pinch-sealed portion and adjacent to the major or longitudinal axis of the lamp.

FIG. 4 is a side view and a front view of a fine finished cartridge-type lamp having point protrusions extending from the pinch-sealed portions, the protrusions being vertically displaced from each other and located adjacent to the major or longitudinal axis of the lamp.

FIG. 5 is a side view and a front view of a fine finished cartridge-type lamp having point protrusions extending from the pinch-sealed portions, the protrusions being horizontally displaced from one another and from the major or longitudinal axis of the lamp.

FIG. 6 is a side view and a front view of a finished cartridgetype lamp having point recesses in the pinch-sealed portion, the protrusions being located at the sealed outer edge of the pinch-sealed portions and adjacent to the major or longitudinal axis of the lamp, thereby forming a notch at that point.

FIG. 7 is a side view and a front view of a finished cartridgetype lamp having point recesses in the pinch-sealed portions, the recesses being located at an intermediate position between the inner and outer sealed edges of the pinch-sealed portion and adjacent to the major or longitudinal axis of the lamp.

FIG. 8 is a side view and a front view of a finished cartridgetype lamp having point recesses in the pinch-sealed portions, the recesses being vertically displaced from each other and located adjacent to the major or longitudinal axis of the lamp.

FIG. 9 is a side view and a front view of a finished cartridgetype lamp having point recesses in the pinch-sealed portions, the recesses being horizontally displaced from one another and from the major or longitudinal axis of the lamp.

The method of forming the various protrusions or recesses at the various locations described in the preceding paragraphs is to induce a flow of molten glass during the pinch-sealing step of the manufacturing process which will result in an envelope of uniform length regardless of the volume of glass making up the pinch-sealed portions. Suitable apparatus for performing this step for' a particular lamp configuration is shown if FIG. 1. Thus, the proper amount of coverage of the contact wires is ensured. Also, the bulb will not be prevented from fitting into certain types of mounting apparatus due to excessive length of the glass-envelope.

Although the contact wires are shown as having the configuration of an open-cornered triangle, it will be readily understood by anyone skilled in the art that numerous'other contact wire configurations might be effectively employed. It will also be appreciated that one or more protrusions or recesses on a single side of the pinch-sealed portions might be used, instead of two protrusions or recesses on opposite sides of the pinch-sealed portion as shown in the drawings. In addition, one or more protrusions may be employed on one surface of the fiat pinch-sealed portion, and one or more recesses on the other surface.

In summary, applicant has devised a method, simple in its practice, to obviate the problems caused by the forced flow of glass during the pinch sealing of lamp envelopes. It will be appreciated that this improvement is readily adaptable to processes other than that disclosed in the copending application referred to to earlier, and that it may be practiced in the manufacture of lamps of varying configuration, e.g., lamps which are pinch-sealed at either fewer or more than two places.

It will be further understood that is it is intended to cover all changes and modifications of the preferred embodiment of the invention, herein chosen for the purpose of illustration, which do not constitute departures from the spirit and scope of the invention.

I claim:

1. In a glass envelope having at least one pinch-sealed portion, the improvement comprising at least one localized alteration means in at least one surface of said at least one pinchsealed portion for controlling the length of the sealed portion, said localized alteration being spaced from the longitudinal sides of said pinch-sealed portion and having a substantially point locus.

2. The improvement according to claim 1 wherein said at least one pinch-sealed portion includes first and second localized alterations each having a substantially point locus and each being situated opposite the other on opposite surfaces of said pinch-sealed portion.

3. The improvement according to claim 2 wherein said first and second localized alterations consist of recesses.

8. The improvement according to claim 1 wherein said at least one pinch-sealed portion includes first and second localized alterations, each having a substantially point locus and each being vertically displaced from the other.

9. The improvement according to claim 8 wherein said firs and second localized alterations consist of recesses.

10. The improvement according to claim 8 wherein said first and second localized alterations consist of protrusions. 

1. In a glass envelope having at least one pinch-sealed portion, the improvement comprising at least one localized alteration means in at least one surface of said at least one pinch-sealed portion for controlling the length of the sealed portion, said localized alteration being spaced from the longitudinal sides of said pinch-sealed portion and having a substantially point locus.
 2. The improvement according to claim 1 wherein said at least one pinch-sealed portion includes first and second localized alterations each having a substantially point locus and each being situated opposite the other on opposite surfaces of said pinch-sealed portion.
 3. The improvement according to claim 2 wherein said first and second localized alterations consist of recesses.
 4. The improvement according to claim 2 wherein said first and second localized alterations consist of protrusions.
 5. The improvement according to claim 1 wherein said at least one pinch-sealed portion includes first and second localized alterations, each having a substantially point locus and each being horizontally displaced from the other.
 6. The improvement according to claim 5 wherein said first and second localized alterations consist of recesses.
 7. The improvement according to claim 5 wherein said first and second localized alterations consist of protrusions.
 8. The improvement according to claim 1 wherein said at least one pinch-sealed portion includes first and second localized alterations, each having a substantially point locus and each being vertically displaced from the other.
 9. The improvement according to claim 8 wherein said first and second localized alterations consist of recesses.
 10. The improvement according to claim 8 wherein said first and second localized alterations consist of protrusions. 